移除单元法中单元失效应变的确定

摘要

To simulate the tensile fracture process of cracked plates using the element removal method, this paper analyses the method of choosing element failure strain and various influencing factors. Resorting to the finite element software,MSC.Dytran,the maximum load,displacement and energy of the cracked plate are calculated,based on which the effects of the material property and grid size on element failure strain are investigated. The deviation of the failure strain under three criterions is discussed. The results show that the failure strain determined by the energy criteria,which considers both the load and displace⁃ment,best agrees with the experimental data,and the mechanical property of cracked plates are also re⁃flected correctly. On the other hand,the maximum displacement criteria provides larger maximum load re⁃sult than expected,which makes it suitable for the numerical calculation that focus on the displacement of cracked plates. Finally,the deviation of the maximum load criteria is too large to reflect the accurate me⁃chanical property of cracked plates. Above all,the element removal method is best suited for simulating the fracture process of large structures.%　　针对移除单元法数值模拟裂纹板拉伸断裂的过程，研究单元失效应变的选取方法及影响因素。采用MSC.Dytran 有限元软件进行数值计算，分别以试验获得的载荷极值、最大伸长量和能量为依据，分析网格尺寸对单元失效应变的影响，讨论3种准则的失效应变计算结果与试验间的误差。结果表明：能量准则的失效应变综合考虑了裂纹板拉伸过程中载荷与位移这两个因素，计算结果能较好地反映裂纹板的力学特性；最大伸长量准则的失效应变计算载荷极值略高于试验值，适用于优先考虑裂纹板伸长位移的数值计算；载荷极值准则的失效应变计算结果偏差较大，难以全面反映裂纹板拉伸断裂的力学特性。结果显示，移除单元法适于模拟大型结构物的破坏过程。